The purpose of this study was to investigate the efficacy of r-metHuG-CSF to correct severe neutropenia secondary to glycogen storage disease (GSD) type 1b and to test the efficacy of G-CSF in correcting neutrophil dysfunction in patiens with GSD type 1b. The study also evaluated the effects of daily G-CSF on the prevention/resolution of secondary outcome variables. This study is now closed. Data analysis is underway.